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This study investigated the acute effects of barefoot (BF) running on biomechanical parameters and cytokine concentrations. Seventy-one habitually shod runners had biomechanical parameters evaluated during running shod (SH) and BF, while a sub-group of 19 runners had their inflammatory profile analyzed before and after a running session, using their habitual shoes or barefoot. Running BF changed spatiotemporal and joint kinematics, including the stride frequency (increased) and length (decreased), and foot strike pattern (more plantarflexed ankle at initial contact). An increased impact force was observed (p < 0.05), while joint moment, power, and work were also affected by BF running: a shift of joint load from the knee and hip to the ankle occurred (p < 0.05). In cytokine levels, maintenance (all cytokines, except Eotaxin, IL-12p40, IL-2, IL5, and MIP-1 beta) or reductions (IL-12p40, IL-2, and IL5) were observed as an acute response to BF running, what means to keep or reduce the levels of pro-inflammatory cytokines and immunological/chemoattraction proteins when compared to SH. Summarily, a single session of BF running may not represent enough stress to induce changes in the inflammatory profile. Besides the increased impact force, the joint load was reduced during short-term BF running. Nevertheless, short-term BF running should be cautiously applied due to the shift of joint load from the knee and hip to the ankle. • Acute barefoot (BF) running increases impact force. • Joint moment, power, and work are also affected by acute BF running. • A shift of joint load from the knee and hip to the ankle is observed. • A single training session of BF running may not represent enough stress to induce changes in the inflammatory profile. [ABSTRACT FROM AUTHOR]

Postural control relies on three principal sensory systems: vision, vestibular and proprioceptive; that are affected by aging. When performing a cognitive task concomitantly with a motor task, those sensory impairments lead to even greater deleterious effects on balance. We aimed to study the effects of a sensory aid (a light touch) on a dual task paradigm and sought to understand the different responses on balance due to aging. Fifty healthy and highly physical active women were divided in two groups: young (N = 25, 24.2 ± 4.0 years) and older adults (N = 25, 67.3 ± 4.2 years). In a random and balanced order, all participants performed five tasks: Stroop test while seated (Seated); Stroop test while standing quiet (ST); Standing quiet (BL); Standing quiet with a haptic input (LT); and Stroop test with a haptic input while standing quiet (SL). In the Stroop test, older women committed more errors (50 vs 11 errors, p < 0.001) and had higher reaction time (1.001 ± 0.191 vs 0.699 ± 0.081 s, p < 0.001). The haptic input (LT) reduced all body sway parameters, in both groups, regardless the condition. This means that postural control under a dual task paradigm (ST) deleterious effect can be mitigated by a haptic input. • Haptic input can mitigate the effects of aging on balance. • Dual task performance is not compromised by the haptic input. • The haptic input mitigates the effects of aging on a dual task paradigm. [ABSTRACT FROM AUTHOR]

Perception of external loads may be a central topic to understand adjustments to the mechanical demands during movement. Nevertheless, the association between the perceived and the real load received is still controversial. This study aimed to correlate vertical ground reaction force (vGRF) to the perception of impact in different regimens of stimulus application. Ten physically active men performed drop jumps from four different heights (0.20, 0.40, 0.60 and 0.80 m). A force plate measured the vGRF, while perception of impact was evaluated through Borg's Ratings of Perceived Exertion. Higher values of maximum vGRF (Fy_max) and impulse of the first 50 ms (I_50), and reduced time to reach Fy_max indicate increased external forces as drop jump height raised. Perception of impact increased gradually with increasing jump height for I_50. Fy_max and I_50 showed moderate to strong correlations to perceived load for 70% and 90% of participants, respectively. Higher and different intensity of stimulus facilitated the perception of impact, presenting moderate to strong correlations to kinetic parameters related to external load during landing from drop jump. Perception of higher impacts could be used as a surrogate to monitor 'real' impacts and possibly also for managing impact-related injury risk. [ABSTRACT FROM AUTHOR]

It has been postulated that the mechanical and neurophysiological effects induced by stretching decrease maximal muscle strength and power. Additionally, the reduction in neural input and muscle stiffness can affect the joint stabilization process. However, there is no evidence available to support this hypothesis. Thus, the aim of this study is to analyze the influence of static stretching on dynamic joint stability. Twenty physically active female university students (22.8 ± 5.3 years; 58 ± 8.8 kg; 1.62 ± 0.07 m) performed a series of static-passive stretching exercises for the peroneus longus and brevis muscles (four repetitions of 30 s). Before and after the stretches, electromyography was performed on both muscles during simulated ankle sprain. Mathematical algorithms calculate the latency and the electromyography activity (RMS). After stretching, the latency increased from 66ms to 73 ms (p = 0.003) for the peroneus brevis muscle and from 70 ms to 79 ms (p = 0.001) for the peroneus longus muscle. The RMS, calculated 100 ms after the simulation, decreased in the peroneus brevis muscle, from 25.05 to 18.16 (p = 0.001), and in the peroneus longus muscle, from 22.84 to 15.61 (p = 0.001). Muscle stretching changed the motor responses of both muscles. The increase in latency and the decrease in RMS indicate that static stretching influences the neuromuscular function involved in the joint stabilization process. [ABSTRACT FROM AUTHOR]

This study evaluated if running in a "transition shoe" commercially available results in intermediate mechanical load upon lower extremities compared to conventional shoe and minimalist shoe/barefoot. Kinematic and kinetic parameters while running in different shoe conditions were compared. Fourteen runners (12 men, 2 women; age=28.4±7.3 years), inexperienced in minimalist shoes and barefoot running, ran on an instrumented treadmill within four experimental conditions (conventional shoe - CS, transition shoe - TrS, minimalist shoe - MS, and barefoot - BF). Running was performed at 9km/h for 10min in each experimental condition. Vertical ground reaction force (VGRF) and two-dimensional kinematic variables of lower limbs (both legs) were recorded. Nine data acquisitions (10s) were conducted for each footwear condition. Transition shoe lead to significant changes in VGRF variables related to impact control, while kinematic parameters were little affected. The TrS had smaller first peak of VGRF (Fy1) than CS (p≤0.001) and higher than MS (p=0.050) and BF (p≤0.001). Time to first peak of VGRF (tFy1) of TrS was smaller than CS (p≤0.001) and higher than MS (p≤0.001) and BF (p≤0.001). The TrS and MS induced to lesser knee flexion (p<0.001) and greater dorsiflexion (p<0.001) than CS and BF. Thus, results suggest the transition shoe (TrS) tested seem to promote an intermediate mechanical load condition only for VGRF parameters, presenting values of impact forces between those found for conventional shoe and minimalist shoe/barefoot. Such knowledge could be useful for the transition process from conventional running shoe to minimalist shoe/barefoot. [ABSTRACT FROM AUTHOR]

An abstract of the article "Plantar pressure distribution in indoor soccer shoes" by Aline Faquin, Júlio Cerca Serrão and Aluisio Vargas Avila is presented.

The development of new transcutaneous techniques of densitometric analysis of bone mineralization has favoured investigations related the study of the structural components of the bone, mainly in the sense of identifying possible influences of the physical activity over the bone modulation between childhood and adolescence. Studies accomplished in the last decades indicate that exercises characterized by bone compression lead to new adaptations of the skeletal struture, turning her more resistant to the external stimulus. Land exercise such as volleyball, basketball, artistic gymnastics and resisted exercises when practiced during the maturational phase, are the most indicated for bone mineral density elevation, for peak bone mass optimization in the adult phase and for osteoporosis prevention in advanced aging. In opposite, there are evidences that aquatic exercises, like swimming, do not present effective contribution for the total bone modulation. Female athletes who practice chronic, repetitive and persistent exercises way, they can too present bone fragility due to reduction of the estrogen secretion consequent of the excessive exercise. The study of maturational processes is complex and multifactorial, so there's a need of more detailed investigations related to the exercise influence in each of the growing phases. [ABSTRACT FROM AUTHOR]